2013- 10- 22
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#121
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:: المشرفة العامة سابقاً ::
الأقسام العامة
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رد: The tenth day of the English competition
اقتباس:
المشاركة الأصلية كتبت بواسطة H N O O
نو خطآ انا اعترض ويقووه 
الاثنين معآآآ  |
Depending on various geographical locations these may change, but for the most part air is made up of 78% nitrogen (N2), 21% oxygen (O2), and trace amounts of carbon dioxide (CO2), methane (CH4), hydrogen (H2), argon (Ar) and helium (He). The CO2, CH4, H2, Ar, and He, when combined together, make up about 1% of our air.
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